Method of relining sewers and water lines without excavation

ABSTRACT

A method is disclosed for relining buried pipeline with interconnectable plastic type pipe sections. The method comprises gaining access to an open end of the buried pipeline, such as through a manhole, passing pipe sections down the manhole and inserting individually each pipe section into the buried pipeline open end. Each pipe section is of a length to permit, within the confines of the manhole, insertion of each pipe section into the pipeline open end. Each pipe is of a diameter to fit within the pipeline. The pipe section to be inserted is interconnected to the pipe section already inserted within the buried pipeline. Such interconnected sections are sequentially moved into the buried pipeline to permit insertion of the next pipe section into buried pipeline until the entire length of the pipeline to the next access area has been relined.

This is a continuation of application Ser. No. 892,875 filed Jan. 13,1986 which is U.S. Pat. No. 4,796,669 and which is a continuation ofapplication Ser. No. 284,442 filed July 17, 1981 now abandoned.

FIELD OF THE INVENTION

This invention relates to a method for relining buried pipelines andproduct used in relining such pipelines.

BACKGROUND OF THE INVENTION

There are many situations where there is a requirement to replace orrepair pipelines in densely populated areas or inaccessible areas. Thenormal procedure for many years, which is particularly troublesome incongested cities, is to close off a street, dig up a buried damagedpipeline, install the new pipeline and repair the street. This iscommonly done with city sewer and storm drain lines. However, there aremany other areas where inaccessible faulty pipelines need to be relined.

To reduce the need to dig a trench along the entire length of thepipeline to be replaced, this has been overcome by a process ofinserting within a pipeline requiring replacement a plastic pipe liner.Such a method of relining sewer pipe is disclosed in Bremner, U.S. Pat.No. 3,602,263. In his method as particularly directed to the relining ofsewer mains, a reaming device is first passed through the old sewer lineto remove tree roots, calcium deposit caked on the pipewalls and thelike. A plastic pipe is passed through the reamed sewer line, theplastic pipe being of a lesser diameter than the reamed sewer line toform the new interior for the sewer line. The plastic piping, as fedinto the sewer line, is commonly of polyethylene pipe where lengths ofpipe are interconnected by the process of butt fusion welding, where theends of pipe lengths to be joined are melted and in their softenedstate, connected to one another. Depending upon the length of the sewerline to be relined, this determines the number of pipe sections whichare joined together. Commonly the pipe sections are of fifty footlengths and are interconnected by using expensive, difficult to operatebutt fusion welding equipment. Such equipment requires skilled personnelon the job site.

Another approach in relining sewer lines and other buried servicepipelines is disclosed in Levens, U.S. Pat. No. 3,950,461 and St. Onge,Canadian patent No. 1,033,197. In these patents, improved techniques aredisclosed for connecting lateral sewer lines to a relined main sewerline. Such interconnection is made from a remote location within thehouse or building via the lateral sewer line.

The drawback of the above processes for relining buried pipelines isthat, aside from the requirement of butt fusion welding to interconnectlengths of pipe to be drawn into the pipeline to be relined, it stillrequires excavation and interruption to the flow of vehicle traffic.

As to the aspect of interconnecting pipe sections, mechanicalinterconnection of pipe sections have been used, such as in the oildrilling field. Drill strings are mechanically interconnected as shownin Knox et al, U.S. Pat. No. 3,359,013, Duret, U.S. Pat. No. 3,508,771and Hokanson et al, U.S. Pat. No. 3,667,784. However, in thesearrangements the drill strings or casing joints are formed of steel andwould be totally unacceptable for use in relining buried pipeline,because of their rigidity. Insofar as mechanical interconnection oflarger diameter plastic pipe is concerned, clamps have been used, forexample, as supplied by DuPont Canada and sold under the trademarkSclairloc. Such couplings add large projections to pipe exterior makingit unacceptable for relining pipelines by insertion renewal.

The method, according to this invention, provides for the relining ofburied pipeline, where access thereto is difficult or impossible byexcavation. The method provides for relining the pipeline withoutdisturbing the surrounding street vehicle traffic by taking advantage ofalready provided accesses to the buried pipelines such as by manholes.

SUMMARY OF THE INVENTION

The method, according to this invention, for relining a buried pipelinewith interconnectable plastic pipe sections comprises gaining access toan open end of the buried pipeline and passing pipe sections through theaccess area. Each pipe section is individually inserted into the buriedpipeline open end, where each pipe section is of a length to permitwithin the confines of the access area insertion of each pipe sectioninto the pipeline open end and is of a diameter to fit within thepipeline. The pipe section to be inserted into the pipeline isinterconnected with a pipe section already inserted in the pipeline. Theinterconnected pipe sections are sequentially moved after eachinterconnection into the buried pipeline to permit insertion andinterconnection of the next pipe section into the buried pipeline.

The length of plastic pipe for use in relining buried pipelines is madefrom a plastic selected from the group consisting of polyethylene,polypropylene and polyvinylchloride. The pipe is substantially straightand has its ends adapted for interconnection of its ends to other likepipe lengths. The mating interconnection of pipe ends retains itsintegrity as interconnected lengths of pipe are moved within the buriedpipeline to reline same. According to an aspect of the invention, maleand female end portions are provided on each length of pipe which form amating interconnectable interfit. Such male and female end portions maybe buttress type threads, whereby relative rotation of each pipe sectionprovides for a secure interconnection of the sections.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are shown in the drawingswherein:

FIG. 1 is an elevation of a job site showing the relining of a buriedpipeline according to the invention;

FIG. 2 is a sectional elevation demonstrating a technique for movingconnected sections of pipe lengths into the buried pipeline;

FIG. 3 shows a plurality of pipe lengths interconnected by cooperationof male and female threads, where relative rotation of the sectionsforms a secure interconnection;

FIG. 4 is a section of two lengths of pipe about to be joined, wheremale and female buttress type threads are provided on theinterconnectable ends;

FIG. 5 shows the interconnection of the pipe ends of FIG. 4;

FIGS. 6 and 7 show a type of snap-fit interconnection of male and femalecomponents;

FIG. 8 shows the ends of two pipe lengths adapted with male and femaleinterconnections;

FIG. 9 shows the wrapping of a bonding agent about the joint to securethe interconnection and;

FIG. 10 is a side elevation of a job site showing the pulling ofinterconnected lengths of plastic pipe into a buried pipeline to berelined.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a typical buried sewer line or stormdrain line isshown for purposes of illustrating the method according to theinvention. It is appreciated, however, that the method is applicable torelining many other types of buried pipelines which, for one reason oranother, are inaccessible, such as, lines for carrying corrosivechemicals, gasolines, oil lines, low pressure waterlines and the like. Atypical street surface 10 has a service vehicle 12 parked adjacent amanhole 14 which provides access to a sewer line 16 which is to berelined. The reason for the reline is usually due to corrosion, cracksresulting in a leak somewhere along the line which must be repaired. Thesections or lengths of pipe generally shown at 18 are stacked behind anoperator 20 who lowers each pipe section 22 down the manhole 14. Anoperator 24 is at the base of the manhole 14 and receives pipe 22 whichis lowered down or through the access. The lengths or sections of pipe22 are as shown and have provided at one end a male threaded portion 26and a female threaded portion at the other end which is more clearlyshown in FIG. 4. The sections of pipe are placed in the buried pipeline16 where each section is interconnected to the other before moving theinterconnected sections sequentially into the pipeline 16. Each lengthof pipe 22 is such that it may be readily maneuvered within the confinesof the lower area 28 of the manhole, so that the pipe may be orientedfor insertion into the open end portion 30 of the pipeline,interconnected to the other sections of pipe and then moving theinterconnected sections into the pipeline.

This procedure is repeated until a sufficient number of pipe lengths 22have been interconnected and inserted into the pipeline to form a lengthof interconnected sections, as generally indicated at 32, so as toproject from the other open end at 34 of the pipeline into the lowerportion 36 of a manhole 38. At this point, the insertion of pipesections is ceased and the connections, if needed, are secured toprovide insertion renewal of faulty buried pipe 16. The ends of the pipelength 32 are sealed to the openings 30 and 34 so that all liquidrunning into the manhole areas 28 an 36 now pass into the interconnectedlength of piping 32. Special grouting materials, which set in water, maybe used to seal the ends of the completed pipe section 32 to theopenings 30 and 34 for the pipeline 16.

It is apparent that this process does not require any excavation of thepipeline system 16, nor does it require any stoppage in flow of watersor liquids along the line 16, since the operator with appropriate attiremay stand at the base of the manhole and insert and interconnect thesesections while liquid runs around the sections along the old pipeline16.

Further aspects of the insertion and interconnection of the pipe lengthsare shown in FIGS. 2 and 3. The base of the manhole is shown at 28 onwhich the workman may stand. Sewer line 40 runs into this area and flowsinto sewer line 16 which has its opening at 30. Each pipe section isinserted in the sewer line 16 as shown at 22. Due to the nature of thepipe being made of plastic such as polyethylene, polypropylene orpolovinylchloride, the interconnected sections of piping 32 may take onvarious slight curvatures in the pipeline 16. The diameter of the pipelength 22 is less than the internal diameter of the pipeline to berelined to permit easy insertion of the sections into the pipeline andalso movement of the interconnected sections 32 along the pipeline. Tofacilitate forcing of the interconnected sections of piping 32 into thepipeline 16, particularly should it have a curvature or bend, a powerdrive device is used. As shown in FIG. 2, the sections 32 are pushedinto the pipe 16 by a power drive in the form of a jack 42 which ispositioned against wall 44 of the manhole 14 and the jack ratchet 46climbs the bar 48 of the jack 42 by operation of the hand lever 50 topush the interconnected pipe sections into the pipeline 16 in thedirection of arrow 52. To protect the threaded end 26 of the pipe 22, aplate 54 may be placed over or adapted to be threaded onto a portion ofthe thread 26 against which the ratchet plate 46 abuts. Once the pipehas been inserted to the desired extent into the pipeline 16, theprotective plate 54 may be removed to permit interconnection of the nextsection of pipe 22.

It is appreciated that other power drive mechanisms may be used to forcethe interconnected piping 32 into the pipeline 16. For example, a devicemay be lowered into the manhole 14 which works on the basis of airpressure or hydraulic pressure to push the interconnected sections intothe pipeline 16.

As shown in FIG. 3, the securing of interconnect sections of pipe 22 toform a length of interconnected sections 32 is shown. In placing andinterconnecting the pipe sections in the pipeline 16, they need not betightly secured to one another simply loosely hand threaded. However,once the piping 32 projects from the other end 34 into the access area36, chain clamps 56 and 58 may be secured over the projecting ends ofthe new pipe liner 32 and counterrotated in the directions of arrows 60and 62 to tighten the threaded interconnections and thus cause anoverall compression in the length of the pipeline in the direction ofarrows 64. It is appreciated that several turns on the ends of theinterconnected sections 32 are required so that there is in essence asequential transfer of torque along the sections as each joint 66 in theseries is firmly secured.

With regard to the tightening of the joint and its manner of operation,this is discussed in more detail with respect to FIGS. 4 and 5. In FIG.4, pipe sections 22 have on their end portions generally designated at68 and 70 a female threaded portion 72 and a male threaded portion 74. Abuttress type thread is provided on each end portion to resistseparation of the interconnected joint 66. The end 70, which includesthe male portions, has a projection 76 which abuts a sealing member inthe form of an "0" ring 78 which is seated against a recess defined byledge 80. The female end portion 68 includes a wedge-shaped projection82 which is received in a wedge-shaped recess 84 of the male portion 70.The dimensional relationship of these projections and recesses is suchto provide a secure interconnection, as shown in FIG. 5. Thewedge-shaped projection 82 firmly seats in the recess 84 in anoverlapping fashion to provide a smooth surface along the joint 66,where there is no bulge in the external diameter of the pipe in the areaof the joint 66. Thus, an essentially smooth surface for theinterconnected sections 32 of the relining pipe is provided so as to beeasily inserted into the pipeline 16. As the sections are tightened onone another, the projection 76 deforms and squeezes the "O" ring seal 78against the ledge 80 to provide an interior seal for the joint 66 tothereby prevent liquids leaking out of the joint. Such an arrangement isparticularly useful when the relined pipeline is used in transportingliquids which may be under low pressure.

With the use of the buttress thread arrangement of FIG. 4, an additionalfeature is realized in that, as shown in FIG. 5, with projection 82seated in the recess 84, upon pushing the interconnect sections 32 intothe pipeline 16, stops are provided so as to maintain integrity of thejoint while being pushed into the pipeline. Such interaction preventsthe female portion of the interconnection sliding on up over the maleportion and resulting in a faulty joint.

Alternative forms of pipe interconnections for the sections of FIG. 1are shown in FIGS. 6 through 9. In FIG. 6, the pipe sections 22 have aformed male portion at 86 and a formed female portion at 88 which have asnap-fit interconnectable relationship. The male portion 86 includes aramp 90 with a recessed portion 92. The female portion 88 includes aramp 94 with inwardly disposed recessed portion 96. When the pipesections 22 are pushed towards one another, the female section 88expands slightly outwardly as the male section 86 contracts slightly topermit the sections to snap over one another. Ramp 94 rides up over ramp90 so that the male projecting portion 90 snaps into the receivingrecess 96 of the female portion, where the interaction of their abuttingshoulders at 98 forms a secure interconnection of the pipe sections 22.The connection is such that the exterior of the joint 66 is essentiallysmooth to provide interconnected sections of piping 32 which isessentially of consistent diameter along the length of the reliner pipe.Such snap interconnections are convenient in situations where a forcingof the pipe sections into the pipeline results in the sections snappingtogether.

FIG. 8 shows another approach to interconnecting of the pipe sections 22where one section has a male portion 100 and the other section has afemale portion 102. The relationship is such to form an interfit, wherethe exterior of the pipeline remains essentially smooth as shown in FIG.9 at joint 66 and the interior diameter is also essentially consistentacross the joint. A bonding agent 104 is applied to the joint 66. Thisbonding agent may be in the form of a special pressure-sensitiveadhesive tape which is wrapped about the joint to form theinterconnection, or it may be of a special material which, afterwrapping about the joint, is shrunk around the joint by the applicationof heat to form a shrink wrap and secure interconnection of the pipesections 22.

Referring to FIG. 10, another aspect of the invention forinterconnecting pipe sections in relining buried pipeline is shown.Sections of pipe 106 may be interconnected mechanically, in accordancewith this invention, and pulled into a buried pipeline 110 which needsto be relined. To facilitate pulling of the sections 106 into the buriedpipeline 110, excavation is required in the area 112 to providesufficient access such that the pipe interconnected sections may curvein the manner shown, as pulled into the pipeline 110. Thus, the pipelineis broken at 114 and 116 to provide an access opening at 116. At themanhole 118, a sheave 120 is secured in the lower area of the manhole at122 and a sheave arrangement 124 is provided at the top of the manholeto guide the cable 126 to a winch not shown. A pulling head 128 issecured to the leading pipe section 106 where the pulling head 128 isadapted to be mechanically connected to the leading pipe section, forexample by way of threading onto the female end portion of a threadedpipe section, such as shown in FIG. 4 at 68.

The pipe sections 106 may be of longer lengths in view of the accessprovided at 112, where the pipeline 110, to be relined in this instance,may be of several hundred feet such as 500 to 1,000 feet of pipe to berelined at one time. This approach is superior to the butt fusionwelding approach, in that no special tools are required because thesections can be readily assembled on site by simply twisting or snappingthe sections together. The buttress thread is particularly useful inproviding the interconnection, because it has a high degree of resistingseparation while being pulled through the pipeline 110. With thisarrangement, the diameter of the pipe sections is such to be slightlyless than the mainline 110. This permits liquid to run around the pipesections as they are being inserted into the pipeline 110.

This approach provides several advantages including the elimination ofany external or internal couplings, where there are no interiorprojections within the pipe which would disturb the flow of liquids. Thepipe sections can be readily dismantled for reservicing, since theplastic material does not corrode. The use of threaded interconnectionsfacilitates bending along the length of interconnected sections as theyare forced around various curves in the pipeline 110.

The method, according to this invention, and the pipe sections thereofprovide for a very useful form of relining pipelines particularly incongested city areas where disruption of the street is kept to aminimum. A service vehicle may be parked at one manhole, an operatorinserts the sections into the pipeline, forces them into position andseals the exposed ends to the manhole openings. This may all beaccomplished in one day, which would normally take at least four timesthat long with prior methods.

Although preferred embodiments of the invention have been describedherein in detail, it will be understood by those skilled in the art thatvariations may be made thereto without departing from the spirit of theinvention or the scope of the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method of relining aburied pipeline with interconnectable plastic pipe sections of anappropriate diameter for insertion within the buried pipeline, eachsection having a male connection at one end and a female connection atthe other end with said female connection and male connection beingsized to cooperate with an opposite connection and form a locked fitbetween said connections such that said connections cannot beinadvertently axially withdrawn one from the other, said methodcomprising bringing short pipe sections to an open end of the buriedpipeline,aligning an individual pipe section with the buried pipelinesuch that the pipe section is on grade with the buried pipeline,effecting a connection between any pipe section previously immediatelyinserted in said pipeline to form the locked fit between the sections,forcing said connected pipe sections into the buried pipeline by eitherpulling or pushing said sections in preparation for the insertion of thenext pipe section into the buried pipeline.
 2. A method as claimed inclaim 1, wherein said step of effecting a locking fit between said pipesections is accomplished by forcing one pipe section into the otheruntil the locked fit is achieved.
 3. A method as claimed in claim 1,wherein said step of effecting a locking fit between said pipe sectionsis accomplished by axially rotating one pipe section relative to theother thereby screwing one section into the other.
 4. A method asclaimed in claim 1, wherein said pipe sections are brought to the openend of a buried pipeline through a manhole associated with the open endof the buried pipeline and said pipe sections are aligned with theburied pipeline within the manhole.
 5. A method as claimed in claim 1,including continuing to insert and lockingly fit pipe sections and movethe sections along the buried pipeline until the leading interconnectedpipe section emerges from a remote opening of the buried pipeline atanother access area.
 6. A method as claimed in claim 1, wherein saidstep of bringing short pipe sections to an open end of a buried pipelineis accomplished by passing said sections individually through anexisting manhole associated with said buried pipeline in preparation foraligning individual sections with the buried pipeline within themanhole.